Kinetic Magnetism at the Interface Between Mott and Band Insulators

TL;DR

This paper investigates how the interaction between a high-density two-dimensional electron gas and localized electrons in a neighboring Mott insulator at their interface can induce and enhance kinetic magnetism, especially ferromagnetism, using a bilayer Hubbard model.

Contribution

It introduces a bilayer Hubbard model at infinite U with potential difference to analyze interface-induced kinetic magnetism, combining analytic and DMRG methods.

Findings

Magnetism, especially ferromagnetism, is significantly enhanced at the interface.

The study's results are relevant to recent experiments on $R$TiO$_3$/SrTiO$_3$ heterostructures.

The interplay of subsystems leads to unique magnetic phenomena at the Mott/band insulator interface.

Abstract

We show that the interplay of a high density two-dimensional electron gas and localized electrons in a neighboring Mott insulator leads to kinetic magnetism unique to the Mott/band insulator interface. Our study is based upon a bilayer Hubbard model at $U=\infty$ with a potential difference between the two layers. We combine analytic results with DMRG simulations to show that magnetism, and especially ferromagnetism, is greatly enhanced relative by the proximity of the two subsystems. The results are potentially relevant to recent experiments suggesting magnetism in $R$TiO$_3$/SrTiO$_3$ heterostructures.